Reworks workflows into script (#661)

* Reworks some workflows to run a script instead

Advantages are:
- Only one set of tests needs maintenance.
- Local results match workflows, no surprises.
- Reduced reliance on GitHub actions.

Fixes #50, #168, #169, #171, #507

* Adds macos to the test matrix

.github/workflows/ci.yml

@@ -0,0 +1,33 @@
+name: Continuous Integration
+
+on:
+  push:
+    branches:
+      - develop
+  pull_request:
+    branches:
+      - develop
+  schedule:
+    - cron: 30 1 * * 2 # every Tuesday at 1:30 UTC
+
+concurrency:
+  group: ci-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
+jobs:
+  runtests:
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
+    permissions:
+      contents: read
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-python@v1
+        with:
+          python-version: "3.10"
+      - run: ./setup.sh
+      - run: rustup component add rustfmt --toolchain nightly
+      - run: rustup component add clippy --toolchain nightly
+      - run: ./run_desktop_tests.sh